Answer:
selection bias.
Step-by-step explanation:
In research, selection bias is described as a bias that is being introduced or implemented by the selection procedure of selecting groups, individuals, or data for analysis purpose in a way that involves proper randomization is not being achieved by the experimenter or researcher, however, making sure that the selected sample doesn't represent the entire population that has been intended by the researcher to be analyzed or studied. selection bias is also referred to as selection effect.
The correct answer is 'selection bias'.